"When I finally realised what had happened in that interrogation room, it was like an 'Oh my God' moment." Former homicide detective

The idea that anyone would willingly confess to a crime they didn't commit sounds unbelievable, particularly when the punishment may be life in prison or even the death penalty.

"They get to a breaking point where they decide that it is in their best interest to confess." Professor of Psychology

But a series of high-profile cases across America has revealed a slew of wrongful convictions based on false confessions and placed the spotlight on a widely used police interrogation technique designed to make people confess.

"Anybody who's been the victim of a high-pressure sales tactic knows what this feels like. Anybody who says that they would never ever confess to a crime that they didn't do, they haven't been under this sort of pressure." Former homicide detective

The technique sees police officers wage psychological war on suspects through a nine step interrogation process.

"If you let him talk, he'll say the words, 'I didn't do it.' And the more often a person says they didn't do it, the more difficult it becomes for us to get a confession." Interrogation training video.

Wrongful conviction investigators say the process is a travesty of justice.

"It is not based on any science whatsoever. It is just based on their own observations. The real science says its baloney, it doesn't work. And, when they have done experiments with it, they pretty much show that the accuracy is like flipping a coin. It's 50/50." Former homicide detective

One man, who spent almost his entire adult life in jail for a murder he didn't commit, tells of how he was convinced to confess to a shocking crime.

"I was just ready to do whatever they wanted me to do. Whatever you want me to sign, I'm signing so, in my mind, once I got an attorney, he would be able to do what's necessary to show that I was innocent, and I didn't commit this crime." Former prisoner

Another, locked up for two decades, say no amount of compensation can match what he has been through.

"They could have offered me 100 million dollars. Would it give me comfort? Yes...but that doesn't give me my years back." Former prisoner.

The families who fought to free them say they were badly let down by law enforcement.

"They took an oath to help, to save lives and fight for people. And they did not do that, not in my son's case. They were comfortable. They were satisfied that they had a man, and that's all they really wanted, was a body. So, they took my son, for 21 years and 12 days."

Lawyers warn that wrongful convictions will continue to occur without changes to the justice system.

"There is a culture of unaccountability. And, police officers know that they can engage in misconduct that has nothing to do with solving a crime and everything to do with pointing the finger at, perhaps, the easiest person to point the finger at. And, there will be no consequence. And so, it happens over, and over, and over in the United States." Lawyer

The Interrogation, a film by Laurent Richard for Premiere Lignes, goes to air on Monday 29th April at 8.30pm. It is replayed on Tuesday 30th April at 1.00pm and Wednesday 1st May at 11.20pm. It can also be seen on ABC NEWS channel on Saturday at 8.10pm AEST, ABC iview and at abc.net.au/4corners.